1. Field of the Invention
The present invention relates to a night-scene light source detecting device and a night-scene light source detecting method for determining whether an image is picked up under irradiation by specific light sources in night scene or not.
2. Description of the Related Art
In the process of image forming by using an image forming device such as a digital camera or a video pickup camera, the wrong white balance processing often occurs, thereby causing image color distortion. Accordingly, night-scene light source detection can be used in a function of intelligent scene identification and automatic white balance controlling of an image forming device such as a digital camera or a video pickup camera, etc.
U.S. Patent Application Publication No. US2009/0153695A1 discloses a night-scene detecting method discussed below, in which if the mean brightness of the picked up image is less than a predetermined threshold and the ratio of the area of high-light zone to the area of all the image is greater than a predetermined threshold, it is determined that the image belongs to a night-scene image.
U.S. Patent Application Publication No. US2009/0185055A1 discloses a night-scene detecting method mainly using six features: 1) brightness value corresponding to the median in the histogram, 2) peak value in the histogram, 3) bottom width of the histogram, 4) proportion of an underexposed region in the histogram, 5) proportion of the left half of the whole histogram, and 6) binarization threshold obtained by using a discriminant analysis method.
The problem commonly existing in the above prior technologies of night-scene detection is simple night-scene detection can only provide necessary parameter information when picking up an image, such as the setting of exposure time, sensitivity or aperture. However, there often exist different light sources in the night scene, and they could cause wrong white balance processing, thereby causing distortion of the image.